Businessman who founded Subway with a $1,000 loan and made it the world's largest restaurant chain

DeLuca's death came two years after Subway said he had been diagnosed with leukemia and was scaling back on his leadership role at the companyWhen he was 17, Fred DeLuca opened a Connecticut sandwich shop. He approached a family friend at a picnic, a nuclear engineer called Peter Buck, and asked him for ideas on how to save money for college. Buck lent him $1,000 and DeLuca used it to open his sandwich shop, which he called Pete's Super Submarines, in Bridgeport, Connecticut.

The business would become the world's largest restaurant chain. On an early radio advertisement, he noticed that "Pete's Submarines" sounded like "Pizza Marines", so he changed the firm's name to "Pete's Subway" and, in 1968, it was shortened again, to "Subway".

"I don't think I ever dreamed of going into business," DeLuca said in 1993. "No one in my family was in business. I knew nothing about making sandwiches, nor the food industry." But he became known as a franchising mastermind whose recruitment of franchisees fuelled the chain's rapid spread. By 2013, Subway was opening 50 new shops a week; Subway shops now serve about 2,800 sandwiches every minute. This month, DeLuca's worth was estimated at $3.5bn (£2.26m).

His death comes at a tough time for the sandwich empire, however. "Subway guy" Jared Fogle, the weight-losing everyman who became the chain's spokesman and most famous face, agreed last month to a plea bargain for possessing child-abuse images and sex crimes.

The chain, which has more than 44,000 shops in 110 countries and more US locations than McDonald's and Starbucks combined, has also struggled to take on rivals. Last year US sales declined by 3 per cent, falling faster than any other of the US's top 25 food chains.

DeLuca died of leukaemia; after his diagnosis in 2013 he stayed on as chief executive, saying last year that he had no plans to retire and would remain "90 per cent involved" in the company's day-to-day affairs. His sister, Suzanne Greco, was named president in June and will now oversee the operations of the sandwich chain.

DeLuca leaves behind a wife and son. In his book Start Small Finish Big: Fifteen Key Lessons to Start - and Run - Your Own Successful Business, he recalled living in public housing in the Bronx as a child, the son of Italian Americans. His father had not graduated from high school but his mother had stressed the importance of education while growing up.

The family moved to Bridgeport, Connecticut when he was in his teens and after he graduated from high school, DeLuca had planned a career in medicine. "It wasn't intended to support me forever," he wrote of Subway.